Extended length hydraulic switch



Feb. 26, 1957 J. A. LUCKEY EXTENDED LENGTH HYDRAULIC SWITCH Filed Jan. 17, 1955 United States Patent Ofifice 2,783,325 Patented Feb. 26, 1957 EXTENDED LENGTH HYDRAULIC SWITCH John A. Luckey, Chicago, Ill. Application January 17, 1955,Serlal No. 482,115

2 Claims. (Cl. 200-83) This invention relates to electrical switches and more particularly to hydraulically operated electrical switches and specifically to an electrical switch built into the end of a length of flexible tubing filled with a hydraulic fluid.

In recent years the need for an extremely sensitive switch which could be used in safety devices or in alarm systems, has become increasingly apparent. Such switches are necessary in order to actuate automatic cutoutsystems on devices such as elevator doors, factory gates, garage doors, and refrigerator and fire doors. So also such devices are needed to actuate automatic cutout or control devices on conveyor lines, large printing presses, or cutting and stamping machines having moving parts near which operators or attendants'must work.

The requirements for such switches include in addition to immediate and sensitive response to actuations, a long or wide area of sensitivity. Thus the switch must be capable of responding to even very light pressures or touches and this over a long or wide surface of contact.

Heretofore pneumatic electrical switches built intolong tubes have been used in various applications, as for example, to sound alarms in gasoline stations and the like. However, such pneumatic switches are incapable of achieving the high degree of sensitivity and triggerquick response required in safety cutout devices or the like as used in connection with the operation of high speed machines and for the protection of the individuals operating such machines. Conrariwise, hydraulically operated switches are sensitive enough to admirably fill such requirements.

It is therefore an important object of this invention to provide a highly sensitive electrical switch, hydraulically operated and capable of adequately filling the requirements specified hereinabove.

A further object is to provide a highly sensitive hydraulically operated electrical switch combined with a tube which isextremely flexible and capable of being bent around curved surfaces and angles, threaded through machines and mounted on almost any type of surface or edging. 7

Still another object is to provide an electrical switch of sufficient sensitivity which is adjustable to permit its being used in connection with various types of cutout safety devices and the like.

Still a further object is to afford-a hydraulically operated electrical switch which may be built into the end of a hydraulic tube the length of which may be extended to any desired length but which will still remain responsive and sensitive to contact at any point on the tube.

Yet another object is to provide a hydraulically operated electrical switch which in addition to performing its primary function, may also be used in connection with a rubber extrusion as an air seal on the edges of doors and the like.

Yet a further object is to afford an electrical switch of the character described which is fully sealed and impervious to weather, oils, soaps, cleaning compounds and .acids, in additionto being both waterproof and dustproof.

Heretofore electrical switches of the character comprising the subject matter of this invention including pneumatically operated switches, could only be adjusted after at least partial dismantling of the device. For example, if it was desired to adjust the sensitivity of the switch, it was often necessary to completely remove the switch from the tube, make the adjustment and then reinsert the switch in the tube and seal the same therein. As a result of the inconvenience of making the adjustment, such switches were rarely adjusted but were merely used primarily as they were made for a single individual application. Thus when the sensitivity requirement changed, a new switch was substituted for the old one rather than merely adjusting the sensitivity of the old one.

It is therefore yet a further object to provide a hydraulically operated electrical switch built into the end of a hydraulic tube and having readily accessible means for adjusting the switch to vary its sensitivity to fit the requirements of the particular application.

An object relating to the aforementioned adjustable characteristic is to construct the switch with a unique adjustable contact comprising a threaded bolt capable of being readily adjusted from the outside of the device to change the proximity of the same to the other member of the contact.

A final object is to afford a hydraulically operated electrical switch of simple, inexpensive, construction, yet highly-sensitive and most effective for the functions for which it is intended.

With the foregoing and other objects in view which will appear as the description proceeds, the invention consists of certain novel features of construction, arrangement and a combination of parts hereinafter fully described, illustrated in the accompanying drawings, and particularly pointed out in the appended claims, it being understood that various changes in the form, proportion, size and minor details of the structure may be made without departing from the spirit or sacrificing any of the advantages of the invention.

For the purpose of facilitating an understanding of my invention, I have illustrated in the accompanying drawings a preferred embodiment thereof, from an inspection of which, when considered in connection with the following description, my invention, its mode of construction, assembly and operation, and many of its advantages should be readily understood and appreciated.

Referring to the drawings in which the same characters of reference are employed to indicate corresponding or similar parts throughout the several figures of the drawings:

Fig. 1 is an enlarged sectional view of a hydraulic tube mounted in a housin member and illustrating the details of construction of the electrical switch portion;

Fig. 2 is a fragmentary View showing one method of mounting the switch on the end of a door;

Fig. 3 is a similar View showing another method of mounting the switch on the edge of a door or the like;

Fig. 4 is a sectional view taken on the plane of line 4-4 in Fig. l of the drawings and viewed in the direction indicated;

Fig. 5 is a similar sectional view but taken on the plane of line 5-5 in Fig. l of the drawings and viewed in the direction indicated; and

Fig. 6 is a partially longitudinally sectional view of a complete hydraulic tube switch with a portion from the center broken away for the purpose of facilitating illustration of the same.

Referring to the several figures of the drawings, reference numeral it indicates generally a hydraulically operated electrical switch comprising a mounting mem ber generally designated by reference numeral 12 having the switch.

3 a hollow tubular portion 14 within which may be positioned a tube 16 made of a flexible material such as, for example, a vinyl plastic. This tube may be filled w1tl1 a hydraulic fluid such as 18 and has inserted into one end thereof an electrical switch construction designated generally by reference numeral 26.

The switch 20 may comprise a hollow tubular housing member 22 which may be made of rubber or other suitable material open at the inner end but closed at the outer end as at 24. Closure member 24 may be formed with two diametrically-opposed openings such as 26 and 28 adapted to receive therethrough the ends of electrical leads such as 30 and 32. The closure member 24 may be further formed with a central larger-diameter opening 34 within which may be positioned an electrical contact bolt 36.

The bolt 36 may be provided with a slotted head 38 and a screw-threaded shank 40. The function of this bolt will become apparent as the description proceeds.

Fitted within the switch housing 22 there may be a short length of rubber tubing such as 42 having its outer end protruding beyond the inner end of the housing 22. Within this tubing 42 may be sealed a longer length of tubing 44 which may be made of a metallic conducting material such as copper. This conductor tube is internally threaded along its entire length with threads adapted to cooperate with the threads 46 of the threaded shank 40 of the bolt 36. g

It should be noted that the conductor tube 44 extends beyond the outer edge 48 of the tube 42 and the end thereof abuts the inner surface of the closure member 24. It should further be noted that the conductor tube 44 is sealed within the rubber tube 42 as with a plastic cement positioned along its entire inner surface as at 50. Thus the conductor tube 44 and the rubber housing tube 42 are cemented together as a unitary component. In an alternative construction the central opening 34 may be enlarged and the outer end of conductor tube 44 extended therethrough.

The inner ends of the electrical leads 3!) and 32 are permanently electrically connected as by soldering one to the conductor tube 44 as at 52 and the other to an electrical contact member 54 as at 56.

The electrical contact member 54 may comprise a strip of copper metal which extends between the outside surface of the tubing 42 and the inside surface of the outer housing tube 22. The end thereof protrudes beyond the inner end of the tube 42 and is formed with its extreme outer end portion 58 bent at right angles to the straight portion 60. The inner surface of the bent portion 58 has afiixed thereto an electrical contact member 62. If desired, strip 54 may be bent in several oblique angles to afford a self-wiping relationship between the contact members.

It will be noted that the contact member 62 is spaced from the inner end of the bolt shank 40 as best illustrated in Fig. l of the drawings. Directing attention again to Fig. l of the drawings, it will be noted that the inner end of the bolt shank 40 comprises one terminal contact and the contact member 62 com-prises the other terminal contact, each of which is suitably connected by -means of their respective electrical leads 3!) and 32 to a power source or within the circuit of an alarm system or cutout or control device.

Mounted over the inner end of the switch contacts is a sensitive rubber diaphragm such as 64 which is integrally formed on the end of a sholt length of tubing 66 adapted to fit over the inner ends of the electrical contact assembly so that the inner end of the tube 66 abuts the inner end of the housing tube 22, thereby completing an enclosed housing for all of the electrical components of It should be noted that the diaphragm 64 is positioned in closely spaced relationship with the electrical "contact member segment 58. The reason therefor will become apparent as the description of the operation of the switch is revealed.

In operation the switch functions as follows. When contact is made with the walls of the tube 16, as by exerting a pressure which may be as slight as one ounce, the exerted force is transmitted through the hydraulic fluid 18 until the same is transmitted to the highly sensitive diaphragm 64. The diaphragm 64 is thereby flexed until it abuts or touches the terminal segment 58. This in turn flexes the terminal member 62 until it touches the outer end of the terminal bolt 36 thereby closing the circuit and energizing the automatic cutout control device or alarm device as the case may be. It should be apparent that the gap between the contacts may be readily adjusted by merely rotating the bolt 36 so that it moves in or out of proximity with the contact member 62. It should further be apparent that since close electrical contact is at all times maintained between the conductor tube 44 and the bolt 36 through the screw-threaded construction, the bolt is actually an integral part of the electrical contact.

It should further be noted that the housing tube 22 is cemented into the end of the tube 16 as at 68 to afford a water-tight connection therebetween.

Although the switch may be used as described hereinabove, if desired the tube 16 may be positioned in the protective sleeve 14 of the mounting member 12. This mounting member 12. This mounting member may comprise a rubber extrusion with the tubular portion 14 ribbed as at 70 and having a pair of divided legs such as 72 and 74 which enables it to be mounted on the leading edge of a member such as a door D shown in Figs. 2 and 3 of the drawings. When so used the encased switch may also serve as a door seal.

In Fig. 6 of the drawings it should be noted that the end of the tube 16 is closed as by heat sealing at 76. Obviously a closed hydraulic tube is essential to the functioning of the switch.

From the above description and drawings it should be apparent that I have provided a novel, highly sensitive, hydraulically-actuated, electrical switch, the applications and functions of which are myriad in number. The switch is embodied in a long flexible tube, thereby affording an area of actuation which is extended in length. The switch may be adjustable to make the same immediately responsive to even the slightest pressure (as little as one ounce) or it may be adjusted to make it less sensitive in accordance with any desired requirement. A novel means of adjustment comprising a two-piece electrical contact, one part of which comprises a headed screwthreaded bolt accessible for adjustment from outside the tube, enhances greatly the universal application thereof by facilitating the adjustment of the same. Additionally a unique but highly practical extruded rubber mounting member is provided for mounting the tube in certain applications as along the edges of doors.

It is believed that my invention, its mode of construction and assembly, and many of its advantages should be readily understood from the foregoing without further description, and it should also be manifest that while a preferred embodiment of the invention has been shown and described for illustrative purposes, the structural details are nevertheless capable of wide variation within the purview of my invention as defined in the appended claims.

What I claim and desire to secure by Letters Patent of the United States is:

1. A hydraulically operated electrical switch comprismg in combination; an elongated plastic tube closed at one end and filled with a hydraulic fluid, a hollow nonconductor tube fitted into the end of said plastic tube, said hollow tube open at the inner end and closed by a closure wall at the outer end, another hollow non-conductor tube fitted into said first-mentioned hollow tube with the end of said second-mentioned tube protruding inwardly beyond the end of said first-mentioned hollow tube, a strip of conducting material positioned between the walls of said hollow non-conductor tubes with the ends thereof protruding beyond each end of said secondmentioned tube, the inner end portion of said strip bent at right angles with said bent end spaced from the end of said second-mentioned tube, a contact point positioned on the bent end of said strip, an internally threaded hollow conductor tube fitted through said second-mentioned non-conductor tube, a pair of electrical leads positioned through said closure wall and connected one to the end of said strip and the other to said conductor tube, a headed bolt threaded through said conductor tube with the headed end protruding out of said end closure and the opposite end positioned in close proximity to said contact point, and a diaphragm fitted over the inner end of said second-mentioned non-conductor tube.

2. In combination with the electrical switch of claim 1, an extruded rubber mounting member comprising a hollow tubular member integrally formed with a pair of mounting flanges.

References Cited in the file of this patent UNITED STATES PATENTS 285,334 Wiswall Sept. 18, 1883 1,699,645 Williams et a1 Jan. 22, 1929 1,719,049 Forsberg July 2, 1929 1,915,167 Salsbury Jan. 20, 1933 1,998,821 Rockwell Apr. 23, 1935 2,153,277 Sharp Apr. 4, 1939 2,251,180 Westley et a1. July 29, 1941 2,263,636 Marsh Nov. 25, 1941 2,437,969 Paul Mar. 16, 1948 2,465,926 Queen et al Mar. 29, 1949 2,757,801 Muggli et a1. Aug. 7, 1956 

